1. Field of the Invention
The present invention relates to a switch device for actuating bicycle gear mechanisms.
2. Description of the Related Art
German Utility Model 90 15 515 discloses a stepping switch intended for controlling bicycle gear mechanisms. A lever of the switch includes a pair of pawls which facilitate the switching of a respectively gear by a desired displacement or a switchover displacement via a toothed disk connected to a cable drum. The actuating displacement of the lever is always equal and the lever always return to its standby position once actuation has taken place. Friction or positioning devices are provided to retain the cable drum in the respectively engaged position. The friction or positioning devices are arranged in the housing of the switch and interact with the cable drum and/or the toothed disk. The pawls are arranged on the lever in relation to the housing such that when one pawl latches into the toothed disk, the other pawl is disengaged by a curved disengagement element connected to the housing. Accordingly, only one of the pawls is operative during each switching operation. The switch is designed as a trigger switch with the possibility of switching in each case one gear in both directions. It is also possible for a number of gear stages to be switched using this solution, although this is irrelevant to the explanation of the switching principle.
The essence of a trigger switch is sufficiently clearly defined in respect of its actuation, but is not realized to a sufficient extent in technical terms as far as the individual gear positions of the cable drum are concerned. The position of the cable drum for the individual gears is formed by a latching device which is only active up to a certain retaining force and possibly also prevents the positioning of precise switchover displacements.
The object of the present invention is to provide a trigger switch connected to a bicycle gear mechanism by a transmission means in which each gear stage is produced with a form fit and thus in a precise manner, the trigger switch including an operating element which returns into its starting position even when more than one gear stage is switched in one of the two directions.
The object of the present invention is achieved by a switch for actuating at least one gear mechanism on a bicycle including a housing and a movement element movable relative to the housing and having a transmission means for controlling the at least one gear mechanism in a tensioning direction and in a release direction. A first pawl is arranged for interacting with a first latching toothing arrangement, wherein the first pawl and the first latching toothing arrangement are operatively arranged for producing a form fit for each individual gear stage of the at least one gear mechanism. The switch further includes a trigger switch means for effecting a switching operation through plural gear stages in said tensioning direction and said release direction by a single switching movement.
According to the present invention, a switch includes a movement element connected to a transmission means whose displacement is clearly carried through to one or more gear stages via a form fit. In addition, the movement element according to the present invention is retained in the respective gear stage via a form fit. Therefore, it is possible to account for switchover displacements of any desired magnitude, especially for the displacement of the movement element in a tensioning direction. The switch may be equipped with a single operating element. Alternatively, the switch may have a tensioning element for tensioning the transmission means and a release element for releasing the transmission means. In each case, the position of the movement element is changed by the engagement of pawls in latching toothing arrangements. The movement element itself is connected to a latching toothing arrangement on a housing via a pawl. The interaction of all the pawls may be controlled. Depending on the movement direction, the pawls are either in engagement or have to be disengaged. The interaction of the pawls is assisted by a transmission element which primarily has the task of accommodating the switching displacements by way of the operating element and of controlling the pawl which is arranged between the housing and the movement element. This control is possible in the release direction by the pawl being disengaged. The disengaged pawl allows the movement element to be pushed via a tensile force of the transmission means to the next gear position. The operating element is retained such as, for example, by springs in a central or rest position into which the operating element returns again, without the action of force, once switching has taken place. In the embodiment having a tensioning element and a release element, these elements may also be retained in a central or rest position by springs. It is irrelevant here whether just one gear stage or a number of gear stages has or have been switched in one direction.
As far as the design of the proposed switch is concerned, the switch according to the present invention may be a twist-grip switch, rotary switch, thumb switch or push-button switch in the translatory or rotary movement direction. Each case involves a housing with a latching toothing arrangement in which a controllable pawl engages, the pawl being connected to the movement element. The controllable pawl is controlled by a disengagement finger on the transmission element. The transmission element is connected by a controllable pawl to either the operating element or the release element. The tensioning element may be connected directly to the movement element via a controllable pawl. The two pawls mentioned above are directed counter to one another and each is controllable by a disengagement nose. The disengagement noses may be connected to the housing since, depending on the operating direction, they have to disengage one pawl or the other when the operating element and/or the tensioning element or control element leave their central position.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.